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New Zealand's longest-running online daily news and commentary publication, now in its 23rd year. The opinion pieces presented here are not purported to be fact but reasonable effort is made to ensure accuracy.

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Magnetism, how weird is that?

1 August 2017

I recall with great joy, the first time I ever encountered the magical effects of magnetism.

How cool was it that two little pieces of metal would at one moment attract each other with an unseen force and then, when reversed, repel with equal force.

Most of the forces that a young lad experiences in the real world (such as a slap on the leg or kick up the backside) could be seen as well as felt -- but magnetism, that was something different.

And how come magnets worked their magic on some things (mainly ferrous metals) but not on others (such as paper, wood, plastic, etc)?

This must surely be the devil's work, this magnetism!

Of course like many curious young lads, I spent many a long hour playing with magnets, reading up on the science and devising cunning experiments to see what could be done with these clever bits of metal. Sadly however, none of the perpetual motion machines I designed ever worked -- but most were at least 90% of the way there :-)

Magnetism is one of those things that continues to fascinate me to this day and the more I learn about it, the more fascinated I become.

Magnets are to DC current what radio-waves and light are to AC -- just the same thing but different in frequency -- which always leaves me struggling to come up with some fantastic new insight into this mysterious force.

Back in the days of my childhood, even the best magnets were pretty weak things. I read about magnets that could "lift 25lbs" in comics and magazines of the era but the only magnets I had were feeble little bits of metal whose force could easily be overcome, even by a pale-skinned geeky kid.

My how things have changed though!

Today's rare-earth magnets are wonders to behold. An order of magnitude stronger than the old alnico magnets of my youth, even a relatively modest sized neodymium magnet can be a real challenge to remove once it has clung to a suitable piece of metal. Even worse, they can inflict significant pain if you are unfortunate enough to get skin caught under them when affixing them to something susceptible to magnetic attraction -- I have the blood blisters to prove it!

Fortunately for us, magnetic fields decay at an inverse-square rate so we're not going to get dragged across the room by our belt-buckles every time someone walks in with a magnet in their pocket -- but modern neodymium magnets are still surprisingly dangerous things to have at your disposal. I find it interesting however, that although there are strict warnings, and even regulations regarding other cool toys such as powerful laser pointers, drones, etc -- high power magnets are still a free-for-all. Maybe it's the inverse-square thing.

When you think about it, huge swathes of our modern technology are reliant on the effects of magnets and magnetism.

The transition to EVs would be impossible without the effects of magnetism -- indeed the bulk of our electricity generation is down to the effect of magnetic fields intersecting conductors.

Radio, TV and the internet are all intimately linked with magnetism, especially rapidly fluctuating magnetic fields such as those which produce radio-wave emissions.

Even the very appearance and survival of life on Earth is down to magnetism, for without the planet's protective magnetosphere, the solar winds would have blown away much of our atmosphere and cosmic rays would have log ago disintegrated the very DNA used to define our existence.

While I think of this... there's a lot of talk about men going to Mars these days and the universally worrying factor is their exposure to cosmic radiation throughout the entire mission. I've always wondered why they simply don't use a magnetic field to protect the occupants of such a craft, a "shield" if you will. Surely such a field could be created by way of electromagnets -- or even a fixed array of powerful rare-earth magnets. By doing this, much of the dangerous stuff could be deflected around the craft in the same way that the Earth's (much weaker) field protects us here on its surface.

Maybe this is impractical or impossible, I don't know. What I do know is that I'd love to understand more about magnetism, as I suspect, would most people.

So why did I write about magnetism today?

Well it was this story on the pages of ScienceDaily. It reminded me that we haven't even come close to making the most of the effects of magnetism yet. Who knows what we'll discover next.

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